Characterization of waveform recorders

Although transient waveform recorders have been in use for more than 15 years, no commonly accepted test procedures were in use for these instruments, particularly for the evaluation of errors associated with dynamic input signals. Within the past few years, however, manufacturers and others have begun to use test methods which involve the application of steady state, repetitive waveforms to evaluate the dynamic performance characteristics of these instruments. Parameters measured with these procedures include quantizing errors, differential linearity errors, integral linearity errors, missing codes, and aperture uncertainty. An advantage of the above method is that a sinusoidal waveform is employed for many of the tests, and these are easily generated and well characterized for frequencies up to 1 MHz. Some disadvantages include the necessity for generating low distortion sine waves at frequencies above 1 MHz, and the difficulty of generating linear ramp-like waveforms with the required linearity at repetition frequencies greater than a fw kilohertz. Several test methods are described.